Biology subjects

Kolic, J.

Publications and source records attributed to Kolic, J..

5 recordsLinked to original sources

bioRxiv2024

HumanIslets: An integrated platform for human islet data access and analysis

Comprehensive molecular and cellular phenotyping of human islets can enable deep mechanistic insights for diabetes research. We established the Human Islet Data Analysis and Sharing (HI-DAS) consortium to advance goals in accessibility, usability, and integration of data from human islets isolated from donors with and without diabetes at the Alberta Diabetes Institute (ADI) IsletCore. Here we introduce HumanIslets.com, an open resource for the research community. This platform, which presently includes data on 547 human islet donors, allows users to access linked datasets describing molecular profiles, islet function and donor phenotypes, and to perform various statistical and functional analyses at the donor, islet and single-cell levels. As an example of the analytic capacity of this resource we show a dissociation between cell culture effects on transcript and protein expression, and an approach to correct for exocrine contamination found in hand-picked islets. Finally, we provide an example workflow and visualization that highlights links between type 2 diabetes status, SERCA3b Ca2+-ATPase levels at the transcript and protein level, insulin secretion and islet cell phenotypes. HumanIslets.com provides a growing and adaptable set of resources and tools to support the metabolism and diabetes research community.

systems biology↗

bioRxiv2024

β-Hydroxybutyrate promotes basal insulin secretion while decreasing glucagon secretion in mouse and human islets.

Dietary carbohydrates raise blood glucose and limiting carbohydrate intake improves glycemia in patients with type 2 diabetes. Low carbohydrate intake (< 25 g) allows the body to utilize fat as its primary fuel. As a consequence of increased fatty acid oxidation, the liver produces ketones to serve as an alternative energy source. {beta}-Hydroxybutyrate ({beta}HB) is the most abundant ketone. While {beta}HB has a wide range of functions outside of the pancreas, its direct effects on islet cell function remain understudied. We examined human islet secretory response to acute racemic {beta}HB treatment and observed increased insulin secretion at low glucose concentrations (3 mM glucose). Because {beta}HB is a chiral molecule, existing as both R and S forms, we further studied insulin and glucagon secretion following acute treatment with individual {beta}HB enantiomers in human and C57BL6/J mouse islets. We found that acute treatment with R-{beta}HB increased insulin secretion and decreased glucagon secretion at physiological glucose concentrations in both human and mouse islets. Proteomic analysis of human islets treated with R-{beta}HB over 72 h showed altered abundance of proteins that may promote islet cell health and survival. Collectively, our data show that physiological concentrations of {beta}HB influence hormone secretion and signaling within pancreatic islets.

cell biology↗

bioRxiv2023

Pharmacological or genetic inhibition of Scn9a protects beta-cells while reducing insulin secretion in type 1 diabetes

Pancreatic {beta} cells are essential for glucose homeostasis and are progressively lost during the development of type 1 diabetes. We previously demonstrated that the use-dependent Na+ channel inhibitor, carbamazepine, protects mouse {beta} cells in vitro and in vivo. Here, we confirmed the protective effects of carbamazepine and other Na+ channel inhibitors in human {beta} cells and investigated the specific role of the Na+ channel {beta} subunit gene Scn9a (Nav1.7) in {beta} cell function and survival. We generated {beta} cell-specific knockout mice on the non-obese diabetic (NOD) background both Ins1Cre knock-in and AAV8-Ins1-Cre approaches resulting in significant reduction of {beta} cell Na+ currents. Ca2+ responses and insulin secretion were significantly reduced, but only under the highest glucose conditions. Notably, carbamazepine treatment did not further alter insulin secretion or {beta} cell survival in Scn9a-knockout islets, indicating that {beta} cell Scn9a primarily mediates this drug's measured effects. Consistent with this, {beta} cell-specific deletion of Scn9a using AAV8-Ins1-Cre significantly reduced diabetes incidence in NOD mice. scRNAseq showed that this protection was associated with reduced Ins2 and increased Cdk8 in {beta} cells. Collectively, our data show that Scn9a plays important roles in {beta} cell excitability and survival during type 1 diabetes, thereby supporting this ion channel as a potential therapeutic target for {beta} cell preservation.

physiology↗

bioRxiv2020

Beta-cell specific insulin resistance promotes glucose-stimulated insulin hypersecretion

Abstract Insulin receptor (Insr) protein can be found at higher levels in pancreatic {beta}-cells than in most other tissues, but the consequences of {beta}-cell insulin resistance remain enigmatic. Ins1cre allele was used to delete Insr specifically in {beta}-cells of both female and male mice. Experimental mice were compared to Ins1cre-containing littermate controls at multiple ages and on multiple diets. RNA-seq of purified recombined {beta}-cells revealed transcriptomic consequences of Insr loss, which differed between female and male mice. Action potential and calcium oscillation frequencies were increased in Insr knockout {beta}- cells from female, but not male mice, whereas only male {beta}InsrKO mice had reduced ATP-coupled oxygen consumption rate and reduced expression of genes involved in ATP synthesis. Female {beta}InsrKO and {beta}InsrHET mice exhibited elevated insulin release in perifusion experiments, during hyperglycemic clamps, and following i.p. glucose challenge. Deletion of Insr did not alter {beta}-cell area up to 9 months of age, nor did it impair hyperglycemia-induced proliferation. Based on our data, we adapted a mathematical model to include {beta}-cell insulin resistance, which predicted that {beta}-cell Insr knockout would improve glucose tolerance depending on the degree of whole-body insulin resistance. Indeed, glucose tolerance was significantly improved in female {beta}InsrKO and {beta}InsrHET mice when compared to controls at 9, 21 and 39 weeks, and also in insulin-sensitive 4-week old males. We did not observe improved glucose tolerance in older male mice or in high fat diet-fed mice, corroborating the prediction that global insulin resistance obscures the effects of {beta}-cell specific insulin resistance. The propensity for hyperinsulinemia was associated with mildly reduced fasting glucose and increased body weight. We further validated our main in vivo findings using the Ins1-CreERT transgenic line and found that male mice had improved glucose tolerance 4 weeks after tamoxifen-mediated Insr deletion. Collectively, our data show that loss of {beta}-cell Insr contributes to glucose-induced hyperinsulinemia, thereby improving glucose homeostasis in otherwise insulin sensitive dietary and age contexts.

physiology↗

bioRxiv2020

Tacrolimus, but not voclosporin, inhibits insulin secretion from human islets at a clinical trough dose

ContextThe incidence of new onset diabetes after transplant (NODAT) has increased over the past decade, likely due to calcineurin inhibitor-based immunosuppressants, including tacrolimus (TAC) and cyclosporin (CsA). Voclosporin (VCS), a next generation calcineurin inhibitor is reported to cause fewer incidences of NODAT but the reason is unclear. ObjectiveWhilst calcineurin signaling plays important roles in pancreatic {beta}-cell survival, proliferation, and function, its effects on human {beta}-cells remain understudied. In particular, we do not understand why some calcineurin inhibitors have more profound effects on the incidence of NODAT. MethodsWe compared the effects of TAC and VCS on the dynamics of insulin secretory function, programmed cell death rate, and the transcriptomic profile of human islets. We studied two clinically relevant doses of TAC (10 ng/ml, 30 ng/ml) and VCS (20 ng/ml, 60 ng/ml), meant to approximate the clinical trough and peak concentrations. ResultsTAC, but not VCS, caused a significant impairment of 15 mM glucose-stimulated and 30 mM KCl-stimulated insulin secretion. This points to molecular defects in the distal stages of exocytosis after voltage-gated Ca2+ entry. No significant effects on islet cell survival or total insulin content were identified. RNA sequencing showed that TAC significantly decreased the expression of 17 genes, including direct and indirect regulators of exocytosis (SYT16, TBC1D30, PCK1, SMOC1, SYT5, PDK4, and CREM), whereas VCS has less broad and milder effects on gene expression. ConclusionsClinically relevant doses of TAC, but not VCS, directly inhibit insulin secretion from human islets, likely via transcriptional control of exocytosis machinery.

cell biology↗